SYNOPSIS
tar [ key ] [ files ]
DESCRIPTION
Tar saves and restores files on magtape or other media. Its actions
are controlled by the key argument. The key is a string of characters
containing at most one function letter and possibly one or more func-
tion modifiers. Other arguments to the command are file or directory
names specifying which files are to be dumped or restored. In all
cases, appearance of a directory name refers to the files and (recur-
sively) subdirectories of that directory.
The function portion of the key is specified by one of the following
letters; use of the leading hyphen is optional:
-r The named files are written on the end of the tape. The -c
function implies this.
-x The named files are extracted from the tape. If the named file
matches a directory whose contents had been written onto the
tape, this directory is (recursively) extracted. The owner and
mode are restored (if possible). If no file argument is given,
the entire content of the tape is extracted. Note that if mul-
tiple entries specifying the same file are on the tape, the
last one overwrites all earlier. Existing target files are
removed before the file in the archive is extracted.
-t The names of the specified files are listed each time they
occur on the tape. If no file argument is given, all of the
names on the tape are listed.
-u The named files are added to the tape if either they are not
already there or have been modified since last put on the tape.
-c Create a new tape; writing begins on the beginning of the tape
instead of after the last file. This command implies -r.
The following characters may be used in addition to the letter which
selects the function desired.
0...9 This modifier selects the drive on which the tape (or other
media) is mounted. Each number selects an `archiveN=' entry
in /etc/default/tar, which is followed by up to four fields:
device name, blocking factor, size in kilobytes, and tape
flag (`n' or `N' for no tape). The entry `archive=' is the
default if neither this modifier nor the f key is given and
the TAPE environment variable is not present. The following
example sets up a tape, a 1.44 MB floppy drive for use with
`0', using a blocking factor of 18, and a 1.2 MB floppy drive
for use with `1', using a blocking factor of 15:
archive=/dev/rmt/c0s0 20 0
chive instead of the default (see the description for the
`0...9' key above). If the name of the file is `-', tar
writes to standard output or reads from standard input,
whichever is appropriate. Thus, tar can be used as the head
or tail of a filter chain. Tar can also be used to move
hierarchies with the command
cd fromdir; tar cf - . | (cd todir; tar xfp -)
b causes tar to use the next argument as the blocking factor
for tape records. The default is device dependent. This
option should only be used with raw magnetic tape archives
(See f above).
l tells tar to complain if it cannot resolve all of the links
to the files dumped. If this is not specified, no error mes-
sages are printed.
o causes tar to set the owner and group of restored files to
those of the invoking user instead of those specified in the
archive. This is the default unless the caller is the super-
user.
p causes tar to set the permission bits of extracted files
exactly to those given in the archive; normally, the current
umask is applied.
i tells tar not to exit when a directory checksum error is
encountered.
e tells tar to exit at several minor error conditions that nor-
mally cause only a warning.
n tells tar that the input file is not a tape. This causes
block sizes to be reported in kilobytes instead of tape
blocks with the `v' modifier.
m causes tar not to restore modification times on extracted
files; the modification time is the time when the file was
restored.
h causes tar to store the target of a symbolic link in the ar-
chive and to follow symbolic links to directories instead of
storing the link itself.
L Same as h.
A causes tar to strip a leading `/' when storing and restoring
pathnames, i.e. to store and extract relative names instead
of absolute ones.
k can be used to create and extract multi-volume archives. The
that is put into the archive before further files specified
on the command line.
X specifies the name of a file that contains pathnames to be
excluded, in the same format as with F. This option may be
specified multiple times, causing pathnames contained in any
of the files to be excluded.
Tar also accepts the following options intermixed with the file names:
-C dir Change the working directory to dir before archiving the file
name immediately following dir; name is interpreted relative
to dir.
-I file Specifies a file with additional pathnames as described for
the F key above, inserted at the current position in the ar-
chive.
The archive format written by tar is expected to be compatible with the
`Extended tar Format' as defined in IEEE Std. 1003.1, 1996, although
the numerical uid and gid fields are always used for extraction, ignor-
ing the symbolic uname and gname fields.
IEEE Std. 1003.1, 2001 pax format extended headers are created by tar
under the following circumstances: A path name exceeds 255 bytes or
does not contain a slash character at an appropriate position, and does
not contain non-UTF-8 characters; the name of a linked file exceeds 100
bytes; a file is larger than 8 GB; a user or group ID exceeds the num-
ber 2097151. When updating GNU or old format archives, no extended
headers are created and any path names are limited to 100 bytes. Most
GNU extensions are supported when reading archives, and Sun extensions
also for appending.
Multi-volume archives are splitted single-volume archives. For an ar-
chive created with
tar cfk /dev/dsk/f03ht 1440 input
it is thus possible to generate a single-volume archive by executing
dd if=/dev/dsk/f03ht bs=1k count=1440 >>singlevolume
once for each floppy disk.
On archives compressed with bzip2(1), compress(1), or gzip(1), the
appropriate decompression program is run automatically with the t and x
keys.
The following keys are supported as extensions:
z causes tar to pipe its output through gzip(1) when creating
archives. When reading archives, this option is ignored.
tar xfop distribution.tar.gz
Write the current directory to the default archive location:
tar c .
If the default location is a floppy drive, the archive is split across
multiple volumes if necessary.
Create a gzip(1) compressed archive of the directory project and its
contents:
tar cf - project | gzip -c > project.tar.gz
ENVIRONMENT VARIABLES
LANG, LC_ALL
See locale(7).
LC_TIME Used for the time string printed with when the keys tv are
given.
SYSV3 If set, old tar format archives are created with `c', and the
meaning of the `e' key is changed such that archiving is
aborted if a file cannot fit on a single volume of a multi-
volume archive.
TAPE Used as default archive if neither the `f' nor the `0...9'
keys are present.
FILES
/etc/default/tar
/tmp/tar*
SEE ALSO
cpio(1), ls(1), pax(1), umask(2)
DIAGNOSTICS
Complaints about bad key characters and tape read/write errors.
Complaints if enough memory is not available to hold the link tables.
NOTES
There is no way to ask for the n-th occurrence of a file.
Tape errors are handled ungracefully.
The u option can be slow.
Use of the r and u options with tape devices requires drives capable of
writing between filemarks.
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